An equation relating viscous flow processes to local microstructure is applied to the viscosity of nine materials belonging to different classes of glass formers. It is seen that the model proposes the correct general behavior for the viscosity and the associated activation energy distributions. The model further explains this behavior in terms of a temperature-dependent ordering process in the structure of the material occurring at low temperatures. Finally, a simultaneous fit of the viscosity and the conductivity of a molten salt yields parameters whose relationships are physically meaningful in terms of the viscous relaxation and conduction relaxation processes.

The viscosity of a 0.60KNQ ,-0.40Ca(NQ melt was measured from 10 " to 10" P by a beam-bending method. In this range, the viscosity exhibited Arrhenius behavior, with an activation enthalpy of 138 kcal/mol. These data joined smoothly with capillary and rotational viscometer data from to 10" P previously reported for this system. The temperature dependence of shear sound wave velocities at 75.2 MHz was measured, and the temperature dependence of the shear modulus from 60" to 120°C was calculated for this melt. The Fulcher equation, In g = A + B / ( T -T O ) , described the temperature dependence of the viscosity of this melt poorly, indicating severe deficiencies in the viscosity theories which predict an equation of this form.